Logo

Compression test (1977 6hp) and spark plug

coteno47

Member
I will receive a compression tester. First time user of this tool.
I understand that I have to remove the 2 sparks plugs and GROUND each of them with DIY jumper to protect the firing coils.

QUESTION: Since there is no stater switch or shutoff button, Is there another way to temporarily stop de sparking process during the compression test and protect the electric components?

Would I be right to unplug the 4 wires that run to the power pack? There is another plug with 3 wires that goes the firing coil ?

Thank you for your advices

Normand
Québec
 
There are two reasons to disable the spark'

1. To protect marginal coils

2. To prevent fire. Fuel vapors shooting out the open plug holes and sparking are not a good situation. Ask me how I know. Yep, danged near set myself afire once.
 
Thank for the security advice.

Without a shot-off button on this engine, what is the easiest way to temporally disable the spark plug firing and protect coils.
Unplug de 4 wires connection before the power pack OR the 3 wires connection going to the 2 firing coils?
Any other easy way?

Normand
Québec
 
Ground the plug wires, by any means you have handy. Best way is with a couple of wires with alligator clips on each end. Quick and dirty way is any metallic object stuck in the plug boots and grounded.
 
Right, it's safe to avoid arcing high voltage, most certainly with gasoline fumes around, but it makes no difference to the power pack whether the spark is directed to ground, or allowed to dead end in the spark plug boots.....this better spells out what I meant to say....thanks, Gator.
 
I hope you got a better compression tester than one I bought. Try it out first on your ,awn mower & see if it gives a realistic number. Mine, brand new, read about 40psi low. Sent it back for refund.
On that motor, you are correct, there is no STOP button.
But does not turning the twist throttle all the way clockwise ground out the ignition?
I was given a ‘75, & the owners manual says to kill the engine, turn the twist grip to STOP.
 
Last edited:
Right, but it doesn't short out the spark...it only retards timing to the point that it won't run.
 
Thank you all for yours advices and comments.
I am happily surprise that a simple and basic post can generate interesting and useful idea.

Have a secure and healthy 2021

Normand
Québec
 
Back
Top